MIDTERM MATH PRACTICE--ANSWERS
Hardy-Weinberg
1) A census of birds nesting on a Galapagos Island revealed that 27 of them show a rare recessive
condition that affected beak formation. The other 63 birds in this population show no beak defect. If this
population is in HW equilibrium, what is the frequency of the dominant allele? Give your answer to the
nearest hundredth.
p = 0.45
2) In 2014 the Career Center High School student body was made up of 88% right handed students.
Being right handed (R) is the dominant trait over being left handed (r).
a. What is p and q for the population of 2014 Career Center High School students. p = 0.65 q = 0.35
b. Find the percent of the student body in 2014 that are homozygous right handed, heterozygous right
handed, and left handed. p2 = 42% 2pq = 46% q2 = 12%
Recombination Frequency
1) The recombination frequency between gene A and gene B is 17.2%, the recombination frequency
between gene A and gene C is 6.8%, and the recombination frequency between gene D and gene C is
27.3%. If the order of these genes on a chromosome is D-B-A-C, then the approximate recombination
frequency between gene D and gene B should be 3.3%.
2) Find the recombination frequency between two genes on the same chromosome in peas given the
following crosses:
P (true-breeders): rough – green pea x smooth – yellow pea
F1: all offspring are rough – green
Test cross: rough – green pea (from F1) x smooth – yellow pea
F2:
115 rough – green
110 smooth – yellow
8 rough – yellow
12 smooth - green
Recombination frequency = 8.2%
Are these genes (seed texture and seed color) likely linked? yes
3) In the nematode, C. elegans, dpy-5 and unc-4 are recessive alleles which confer the phenotypes
of a dumpy body and uncoordinated movement, respectively. A wild-type nematode that is
heterozygous for both genes is test-crossed with a dumpy-uncoordinated nematode and yields the
following progeny:
Phenotype
# Progeny
Wild-type
243
Dumpy - Uncoordinated
239
Dumpy
251
Uncoordinated
242
What is the recombination frequency for these two genes? 50.6%
Would you say that these two genes are linked? no Why/why not? R.F. is >50%.
If they are linked, how many map units apart are they on the chromosome? 50.6 m.u.
Chi-Square
1) In a certain species of flowering plant, incomplete dominance is observed involving the white allele
‘A’ and the red allele ‘a’. A student performed a cross between two pink-flowered plants. When
planted, the 152 seeds that were produced from the cross matured into 42 plants with white flowers, 37
plants with red flowers, and 73 plants with pink flowers.
Calculate the chi-squared value for the hypothesis that incomplete dominance governs the flower-color
gene. Give your answer to the nearest tenth. 0.6 (critical value = 5.99)
Based on your result, the null hypothesis is __________________. (accepted/rejected)
2) In corn, purple kernel color is dominant to yellow kernel color, while smooth kernel texture is
dominant to shrunken kernel texture. A large ear of corn has 200 Purple & Smooth kernels, 228 Purple
& Shrunken kernels, 182 Yellow & Smooth kernels, and 146 Yellow & Shrunken kernels. This ear of corn
was hypothesized to have been produced by a dihybrid testcross (PpSs x ppss.)
Calculate the chi-squared value for the hypothesis that this particular ear of corn was the progeny of the
dihybrid testcross PpSs x ppss. Give your answer to the nearest tenth. ___18.7___ (critical value = 7.82)
Based on your result, the null hypothesis is __________________. (accepted/rejected)
Degrees of Freedom
p
1
2
3
4
5
6
7
8
0.05 3.84 5.99 7.82 9.49 11.07 12.59 14.07 15.51
0.01 6.64 9.32 11.34 13.28 15.09 16.81 18.48 20.09
Genetic probabilities
What is the probability the parents shown below would create the genotypic offspring listed?
Show your work.
HhOoLlIiDdAaYy x HhooLliiDdAayy
1. HhOoLlIiDdAaYy = 1/128
2. hhoolliiDdAayy = 1/512
3. HhOoLLIiDDaaYy = 1/1024
Free Energy
1) The phosphorylation of glucose occurs via dehydration synthesis as follows:
glucose + Pi  glucose-6-phosphate + H2O
ΔG = +8.0 kcal/mole
The breakdown of ATP occurs via hydrolysis as follows:
ATP + H2O  ADP + Pi ΔG = -7.3 kcal/mole
Calculate the total ΔG of the reaction. Does the hydrolysis of ATP provide sufficient energy to power the
synthesis of glucose-6-phosphate? Why or why not? ΔG = +0.7 kcal/mole; insufficient energy since ΔG
is positive/still overall endergonic
2) The Gibbs free energy value of an anabolic pathway required to build the amino acid isoleucine is as
follows: ΔG = +10.3 kcal/mole
What is the minimum Gibbs free energy value required for a coupled catabolic reaction that will allow
the aforementioned anabolic reaction to proceed to completion? ΔG = -10.4 kcal/mole
Osmosis
1.7M sucrose
0.6M starch
0.7M NaCl
0.3M sucrose
1.4M starch
0.9M NaCl
The initial concentration of Side A and Side B are indicated above on either side of the U-tube.
The membrane shown is permeable to sucrose and NaCl but not starch.
Initially,
which side is hypertonic? A
what is the molarity of the hypotonic side? 2.6 M
Please use the correct letters to fill in the blanks below.
In order to reach equilibrium:
sucrose will move from side A to side B.
starch will move from side --- to side ---.
NaCl will move from side B to side A.
After this system reaches equilibrium:
what is the molarity of each side? A = 2.8 M B = 2.8 M
which side will lose water? A
Reaction Rates
An experiment was conducted to measure the amount of oxygen used by mealworms over time at two
different temperatures. Create a double-line graph displaying these results.
Temp
(°C)
18o C
38o C
Time
(min)
0
5
10
15
20
0
5
10
15
20
O2 used
--0.04 mL
0.06 mL
0.10 mL
0.14 mL
--0.16 mL
0.30 mL
0.44 mL
0.60 mL
 For the entire course of the experiment, what was the rate (with proper units) of oxygen
consumption by the crickets at 18o C? 0.007 ml/min At 38o C? 0.03 mL/min
Cell counts
1. A fertilized egg (zygote) undergoes 6 rounds of cleavage including cell partitioning. After the 6th
round, half of the cells divide again while the remaining cells undergo apoptosis. After this
event those remaining cells undergo 3 more rounds of cleavage. How many cells are present
after these events? 512
2. During embryonic paw formation in Timon, a meerkat, there are initially 325 cells between the
first 2 digits of the paw. Each of these cells and their subsequent daughter cells must undergo 4
rounds of cell division to provide enough cells for proper paw development. Next, differential
gene expression initiates apoptosis causing the loss of 70% of the cells. How many cells remain
after these events? 1560